export interface SubstitutionResult {
    index: number;
    contextRange: [number, number];
}

/**
 * Information about ligatures found in a sequence of text
 */
export interface LigatureData {
    /**
     * The list of font glyphs in the input text.
     */
    inputGlyphs: number[];

    /**
     * The list of font glyphs after performing replacements for font ligatures.
     */
    outputGlyphs: number[];

    /**
     * Sorted array of ranges that must be rendered together to produce the
     * ligatures in the output sequence. The ranges are inclusive on the left and
     * exclusive on the right.
     */
    contextRanges: [number, number][];
}

export interface Font {
    /**
     * Scans the provided text for font ligatures, returning an object with
     * metadata about the text and any ligatures found.
     *
     * @param text String to search for ligatures
     */
    findLigatures(text: string): LigatureData;

    /**
     * Scans the provided text for font ligatures, returning an array of ranges
     * where ligatures are located.
     *
     * @param text String to search for ligatures
     */
    findLigatureRanges(text: string): [number, number][];
}

export interface Options {
    /**
     * Optional size of previous results to store, measured in total number of
     * characters from input strings. Defaults to no cache (0)
     */
    cacheSize?: number;
}

export interface LookupTree {
    individual: {
        [glyphId: string]: LookupTreeEntry;
    };
    range: {
        range: [number, number];
        entry: LookupTreeEntry;
    }[];
}

export interface LookupTreeEntry {
    lookup?: LookupResult;
    forward?: LookupTree;
    reverse?: LookupTree;
}

export interface LookupResult {
    substitutions: (number | null)[];
    length: number;
    index: number;
    subIndex: number;
    contextRange: [number, number];
}

export interface FlattenedLookupTree {
    [glyphId: string]: FlattenedLookupTreeEntry;
}

export interface FlattenedLookupTreeEntry {
    lookup?: LookupResult;
    forward?: FlattenedLookupTree;
    reverse?: FlattenedLookupTree;
}